🔀

Git & GitHub Deep Dive

Git install · user config · git init · first commit

Chapter 1 — Getting Started

This is the first chapter of Git. Through the simplest possible workflow, we walk through one full cycle: **write the project skeleton → commit → run**.

installconfiginitcommit

Duration

⏱ 1-2 hours

Level

📊 Beginner

Prerequisite

🎯 None

Outcome

Install Git and make your first repo & commit

What you'll learn

1Understand the basic structure of a Git project (`#include`, `main`, `printf`, `return`) — wait, that was for C. Here: `git init`, `git add`, `git commit`, `git status`, `git log`.
2Install and configure Git on your machine.
3Use `git config` to set up your name and email.
4Create your first repository and commit using just the terminal.
5Understand escape concepts like Working Directory / Staging / Repository.

Why Start with This?

Even before knowing every command, getting the **first cycle (write → stage → commit → log)** working end-to-end already proves that your environment (Git, PATH, encoding) is sane. That's worth more than memorizing syntax.

Core Concepts

1) Installing Git

Windows installers

Tool	Installer	Description	Official download
Git for Windows	`Git-2.52.0-64-bit.exe`	Git CLI + Git Bash. Required to run git commands on Windows.	git-scm.com/install/windows
TortoiseGit	`TortoiseGit-2.18.0.1-64bit.msi`	GUI client that integrates Git into Windows Explorer. Lets you commit, view log, and diff with the mouse — handy if you're not yet comfortable with the command line. Install after Git for Windows.	tortoisegit.org/download

ℹ️

Install order (Windows): Git for Windows first, then TortoiseGit. TortoiseGit uses Git for Windows as its backend, so Git must be installed first.

macOS / Linux

bash

# macOS
brew install git

# Ubuntu / Debian
sudo apt update && sudo apt install git

Verify:

bash

git --version
# git version 2.44.0

2) Global user setup

Every commit you make embeds the author. Set them once globally:

bash

git config --global user.name  "John Doe"
git config --global user.email "john@example.com"

# Check
git config --list --global

Scope	Applies to
`--global`	All your repositories
`--local`	The current repository only (`.git/config`)
`--system`	The whole machine

3) Initializing a repository (`git init`)

bash

mkdir my-project
cd my-project
git init
# Initialized empty Git repository in .../my-project/.git/

Once a `.git/` folder exists, Git starts tracking this directory.

4) Your first commit

text

working directory → (git add) → staging area → (git commit) → repository

bash

echo "# My Project" > README.md
git add README.md
git commit -m "docs: add README"

5) The three areas

Area	What it holds
Working directory	The actual files on disk
Staging area	Changes queued for the next commit
Repository (`.git`)	The committed snapshots, kept permanently

Examples

Example 1 — `ex01_setup.sh`: Verify Git version and current user config

bash

#!/usr/bin/env bash
set -euo pipefail

echo "=== Git version check ==="
git --version

echo ""
echo "=== Current global user config ==="
git config --global user.name  || echo "(user.name not set)"
git config --global user.email || echo "(user.email not set)"

**Output**

text

=== Git version check ===
git version 2.44.0

=== Current global user config ===
John Doe
john@example.com

Key: `git config --global` values can be queried any time.

Example 2 — `ex02_init.sh`: Initialize a temp repo and commit

bash

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
echo "Working directory: $REPO"
cd "$REPO"

git init
git config user.name  "Demo User"
git config user.email "demo@example.com"

echo "# Hello Git" > README.md
git add README.md
git commit -m "chore: initial commit"

echo ""
echo "=== Commit list ==="
git log --oneline

**Output**

text

Working directory: /tmp/tmp.XyZ123
Initialized empty Git repository in /tmp/tmp.XyZ123/.git/
[main (root-commit) a1b2c3d] chore: initial commit
 1 file changed, 1 insertion(+)
 create mode 100644 README.md

=== Commit list ===
a1b2c3d chore: initial commit

Key: `git init` → `git add` → `git commit` is the basic cycle.

Example 3 — `ex03_status.sh`: Observe the three areas

bash

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
cd "$REPO"
git init -q
git config user.name "Demo User" && git config user.email "demo@example.com"

echo "file1" > a.txt
echo "[1] After adding file (status)"
git status

git add a.txt
echo ""
echo "[2] After git add (status)"
git status

git commit -q -m "add a.txt"
echo ""
echo "[3] After commit (status)"
git status

**Output**

text

[1] After adding file (status)
On branch main
Untracked files:
  a.txt

[2] After git add (status)
On branch main
Changes to be committed:
  new file:   a.txt

[3] After commit (status)
On branch main
nothing to commit, working tree clean

Key: `git status` tells you which of the three areas your file is in.

Example 4 — `ex04_inspect.sh`: Inspect commit history

bash

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
cd "$REPO"
git init -q
git config user.name "Demo User" && git config user.email "demo@example.com"

echo "first content" > file.txt
git add file.txt && git commit -q -m "feat: first file"

echo "second line added" >> file.txt
git add file.txt && git commit -q -m "feat: add second line"

echo "=== git log --oneline ==="
git log --oneline

echo ""
echo "=== git show HEAD ==="
git show HEAD

**Output**

text

=== git log --oneline ===
b2c3d4e feat: add second line
a1b2c3d feat: first file

=== git show HEAD ===
commit b2c3d4e...
Author: Demo User <demo@example.com>
Date:   ...

    feat: add second line

diff --git a/file.txt b/file.txt
...
+second line added

Key: `git log` shows commits in reverse order; `git show HEAD` shows the latest commit's diff.

Through a different lens

Git concept	Everyday analogy
Repository	A photo album
Commit	A single photo
Staging area	Print-ready tray
`git add`	Putting a photo into the tray
`git commit`	Pasting the photo into the album

Common mistakes

**Committing without `git add`** — nothing is staged, you get "nothing to commit".
**No user.name/email** — the commit fails with "Please tell me who you are".
**Running `git init` in your home directory** — every file becomes tracked, `.git` grows huge.
**Blank commit message** — without `-m`, the editor opens; saving with an empty message aborts the commit.
**`--global` vs `--local` confusion** — on a work machine you might accidentally commit with a personal email.

Recap

`git config --global user.name/email` sets the author.
`git init` → `git add` → `git commit` is the basic cycle.
`git status` shows the three-area state; `git log` shows commit history.
`git show <commit>` displays the diff of a specific commit.

Try it

bash

cd src
chmod +x ex01_*.sh ex02_*.sh ex03_*.sh ex04_*.sh
./ex01_setup.sh
./ex02_init.sh
./ex03_status.sh
./ex04_inspect.sh

Stretch:

Change your editor: `git config --global core.editor "vim"`.
Try a graph view: `git log --oneline --graph --all`.

💻 Examples

Runnable examples — see the output yourself.

ex01_setup.sh— Verify Git version and current user config

CODE

#!/usr/bin/env bash
set -euo pipefail

echo "=== Git version check ==="
git --version

echo ""
echo "=== Current global user config ==="
NAME=$(git config --global user.name 2>/dev/null || true)
EMAIL=$(git config --global user.email 2>/dev/null || true)

if [ -z "$NAME" ]; then
 echo "user.name: (not set)"
else
 echo "user.name: $NAME"
fi

if [ -z "$EMAIL" ]; then
 echo "user.email: (not set)"
else
 echo "user.email: $EMAIL"
fi

echo ""
echo "=== How to set ==="
echo " git config --global user.name \"John Doe\""
echo " git config --global user.email \"john@example.com\""

▶ Output

=== Git version check ===
git version 2.44.0

=== Current global user config ===
John Doe
john@example.com

ex02_init.sh— Initialize a temp repo and commit

CODE

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
echo "Working directory: $REPO"
cd "$REPO"

git init -b main
git config user.name "Demo User"
git config user.email "demo@example.com"
 git config commit.gpgsign false

echo "# Hello Git" > README.md
git add README.md
git commit -m "chore: initial commit"

echo ""
echo "=== Commit list ==="
git log --oneline

echo ""
echo "=== .git ==="
ls .git/

# cleanup
rm -rf "$REPO"
echo ""
echo " directory done"

▶ Output

Working directory: /tmp/tmp.XyZ123
Initialized empty Git repository in /tmp/tmp.XyZ123/.git/
[main (root-commit) a1b2c3d] chore: initial commit
 1 file changed, 1 insertion(+)
 create mode 100644 README.md

=== Commit list ===
a1b2c3d chore: initial commit

ex03_status.sh— Observe the three areas

CODE

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
cd "$REPO"
git init -q -b main
git config user.name "Demo User"
git config user.email "demo@example.com"
 git config commit.gpgsign false

echo "file1" > a.txt

echo "[1] After adding file (status) (Untracked)"
git status

git add a.txt
echo ""
echo "[2] After git add (status) (Staged)"
git status

git commit -q -m "add a.txt"
echo ""
echo "[3] After commit (status) (Clean)"
git status

echo "edit content" >> a.txt
echo ""
echo "[4] file edit (after) status (Modified)"
git status

rm -rf "$REPO"

▶ Output

[1] After adding file (status)
On branch main
Untracked files:
  a.txt

[2] After git add (status)
On branch main
Changes to be committed:
  new file:   a.txt

[3] After commit (status)
On branch main
nothing to commit, working tree clean

ex04_inspect.sh— Inspect commit history

CODE

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
cd "$REPO"
git init -q -b main
git config user.name "Demo User"
git config user.email "demo@example.com"
 git config commit.gpgsign false

echo "First content" > file.txt
git add file.txt && git commit -q -m "feat: first file"

echo "Adding second line" >> file.txt
git add file.txt && git commit -q -m "feat: add second line"

echo "=== git log --oneline ==="
git log --oneline

echo ""
echo "=== git log --stat ==="
git log --stat --oneline

echo ""
echo "=== git show HEAD ==="
git show HEAD

echo ""
echo "=== git show HEAD~1 ( (before) commit) ==="
git show HEAD~1 --stat

rm -rf "$REPO"

▶ Output

=== git log --oneline ===
b2c3d4e feat: add second line
a1b2c3d feat: first file

=== git show HEAD ===
commit b2c3d4e...
Author: Demo User <demo@example.com>
Date:   ...

    feat: add second line

diff --git a/file.txt b/file.txt
...
+second line added

📝 Exercises

Try them yourself first, then open the solution to compare.

Exercise 1

Problem 1 (hw01.sh)

Goal: Set your own name and email as Git's global config, then verify the result.

Requirements

Filename: hw01.sh

Sample I/O

# Expected output (your own name/email)
user.name=John Doe
user.email=john@example.com

▶Toggle solution

SOLUTION

#!/usr/bin/env bash
set -euo pipefail

# (before) user.name · user.email setup (after) check
git config --global user.name "John Doe"
git config --global user.email "john@example.com"

echo "=== (before) Git setup check ==="
git config --list --global | grep -E "^user\."

▶ Output

# Expected output (your own name/email)
user.name=John Doe
user.email=john@example.com

Exercise 2

Problem 2 (hw02.sh)

Goal: In a fresh temp directory, create a new Git repo, write a `README.md`, make the first commit, and inspect the log.

Requirements

Filename: hw02.sh

Sample I/O

# Expected output
Initialized empty Git repository in /tmp/tmp.XXXXX/.git/
a1b2c3d docs: initial README

▶Toggle solution

SOLUTION

#!/usr/bin/env bash
set -euo pipefail

REPO=$(mktemp -d)
echo "repository : $REPO"
cd "$REPO"

git init -b main
git config user.name "John Doe"
git config user.email "john@example.com"
 git config commit.gpgsign false

echo "# My first repository" > README.md
git add README.md
git commit -m "docs: initial README"

echo ""
echo "=== commit log ==="
git log --oneline

rm -rf "$REPO"
echo "cleanup done"

▶ Output

# Expected output
Initialized empty Git repository in /tmp/tmp.XXXXX/.git/
a1b2c3d docs: initial README

Example code / lecture materials

All lecture materials and example code are openly available on GitHub.

View on GitHub ↗